The Corrupt Officer mission seems to have a small bug in it. After interrogating the officer and knocking him unconscious your next objective is to leave the mansion covertly. There's a red arrow marking where you should go to fulfill this objective but as I managed to sneak past the door guard (I have a relatively high hide skill for my scout) and covertly leave the mansion the game states that I haven't finished the "critical objective".

As I found out from the other forums, the key is to jump out of the second floor window, from the room the officer is. Pick up the unconscious officer go next to a window and move. The rotation of the officer should break those locked windows.

To jump off a second floor window, alt+move through the window (you'll take a small damage). Now you're ready to head out to the exit.

OR you can always go in guns blazing and forget that "covertly" crap.

hahahahaha. Classic moment in gaming.
Loving the physics in this game. I killed a sentry in a tower with a glass window behind him, BANG! he fell backward, broke the glass, literally flew out the window and bounced a few times on the ground.

Destructible environs means you can shoot up and punch holes on floorboards of the 2nd floor, then climb up that way.

Hmm. Never actually tried to punch through floorboards but I'm sure to check it our right away :) Anyway my Scout's silenced SMG was unable to actually create a hole into the floor (I tried).

As a Finn myself, I've also enjoyed the weird Finnish you hear from Lt. Olli. Probably it was rather hard for Nival to find a good finnish speaker, even though we are neighboring countries :)

One of my guys got sprayed by a hidden enemy from one floor up using an MP40 (enemy AI soldier must've heard him somehow?). Lots of bullet holes but no actual crack on the wood floor.

Pretty sure machineguns like Bren/BAR can punch ceilings & floors though, I've done it a few times. They were wood floors though, not sure abt concrete.
They can be necessary if the only stairwell in the building is destroyed by a grenade and you need another place to climb.

I understood you wrong there :) I actually thought about punching through the floor, with your fists. Wouldn't be suprised to see even that happening in a Nival game :D

In Sentinels the AI is more likely to shoot according to what they hear, ie. if you shoot them with a silenced weapon and remain hidden they might still burst a few rounds to your direction.

I can't remember if the original game had a Penetration value for weapons. In Sentinels they have a Penetration value which determines can it go through a brick wall for example. MG42 can go through bricks and heavier obstacles where as STEN MKIII can barely go through a wooden floorboard.